Safety restraint systems which self-actuate from an undeployed to a deployed state without the need for intervention by the operator, i.e. passive restraint systems, and particularly those passive restraint systems incorporating inflatable bags or cushions commonly referred to as airbags, have been devised for automotive vehicles. In such system, one or more airbags are stowed in respective storage areas within the passenger compartment of the vehicle. Upon actuation, the one or more airbags are deployed out into the vehicle passenger compartment through a respective opening or openings in the vehicle interior.
Vehicular inflatable restraint systems generally include multiple crash sensors generally positioned about or mounted to the frame and/or body of the subject vehicle and serve to sense sudden decelerations by the vehicle. Upon detection of a sudden deceleration, such as in a collision, the airbag or airbags are rapidly inflated and deployed in positions to cushion the driver and/or passengers from injury-causing contact with the interior structure of the vehicle.
In general, an airbag for the protection of a front seat passenger, i.e. a passenger side airbag, is typically mounted in a storage compartment behind the instrument panel or dashboard of the vehicle. Such airbags are normally housed in an uninflated and folded condition to minimize space requirements.
Such airbags are generally stowed out of sight, thereby reducing the potential for intentional and unintentional tampering therewith. In the normal operation of the vehicle, prior to deployment of the airbag, a cover door or some form of closure member covers the opening wherethrough, upon actuation, the airbag is deployed. Consequently the closure is of necessity generally exposed within the interior of the vehicle.
The interior trim structure of vehicles, particularly the trim panel also referred to as the instrument panel or dashboard, wherein the opening for airbag deployment is often desirably located and in which the cover door for this opening is situated, is commonly comprised of several layers including a substrate, an overlying foam padding material, and an outer skin or trim covering.
In the interest of minimizing the visual (i.e. "look") and tactile (i.e. "feel") impressions of the presence of the deployment cover door and the opening associated therewith, it has been generally desired that the cover door be designed to match or otherwise be compatible with the interior design of the vehicle. Unfortunately, due largely to the mechanics normally associated with cover door design and operation, it is frequently difficult to closely match the look and feel of the instrument panel and other trim panel surfaces to the desired extent.
Upon actuation, the cover doors are typically opened as a result of the force exerted thereon by way of the airbag inflating thereagainst. In practice, it is generally desired that deployment of the inflating airbag not be appreciably slowed by resistance of the cover door to opening. That is, the cover door is designed to permit the near instantaneous deployment of the airbag into the passenger compartment. This near instantaneous deployment of the airbag through the cover door is generally made possible by the presence of propagation tear lines in one or more of the substrate layer, foam padding layer and the outer skin layer. Although there have been various attempts to provide such tear propagation lines for the cover door in such a manner that the presence of the door would not "show" or be visible through or detectable in the outer skin layer of the instrument panel or dashboard of the automotive vehicle, these attempts have not been totally successful. In general, such attempts have resulted in cover doors whose presence in the instrument panel or dashboard are evident to or readily detectable by an observer due to the presence of slight to moderate depressions in the outer skin layer of the panel or dashboard corresponding to the location of the invisible tear propagation lines of the cover door. It would therefore be desirable to provide such an invisible cover door with tear propagation lines that do not "show" or are not detectable through the outer skin layer of the instrument panel or dashboard.
As earlier described, the airbag deployment process is of necessity a very rapid process and, at least partially as a result thereof, commonly results in the cover door or doors opening with a large amount of force and energy. The rapidity of the deployment process, if not fully accounted for in the system design, can result in the cover door tearing in an undesired and/or uncontrolled manner. Undesired and/or uncontrolled tearing of the closure in turn can result in the cover door breaking into or forming separate pieces which can then act as projectiles which would be capable of damaging or hurting vehicle occupants. Fragmentation associated with cover door opening can be especially pronounced with respect to foam padding material from the trim structure in the area adjacent the airbag deployment cover door. Additionally, the inclusion of a layer of foam padding in a cover door itself, so as to approximate the feel provided by the foam of the trim structure, can prove troublesome as the opening of such a closure could result in fragmentation of the closure foam material.
Thus, an additional need exists for an efficient and economical arrangement for providing a cover door in an interior trim structure of an automotive vehicle for the deployment of an airbag therethrough. Preferably, such an arrangement minimizes the visual and/or tactile impression of the presence of the cover door and both the airbag deployment opening and airbag thereunder and which also does not result in significant fragmentation and projection of such fragments into the passenger compartment upon the opening thereof.